Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Colloids”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources
PubMed1993

99mTc colloid and 99mTc IDA imagings in diffuse hepatic disease.

Ninety-six patients with various diffuse hepatic diseases were observed using both 99mTc colloid and 99mTc iminodiacetic acid (IDA), focusing on the potential etiologies of the disease process as well as its chronicity and severity. The presence of acute hepatic disease was more sensitively depicted with 99mTc IDA than with 99mTc colloid. In chronic hepatic disease, on the other hand, 99mTc colloid and 99mTc IDA demonstrated a similar sensitivity. The potential etiology of the disease process (differential diagnosis) and the chronicity of the disease could be evaluated better with 99mTc colloid. Among the patients with different stages of liver cirrhosis, however, 99mTc IDA significantly discriminated the severity of the hepatic disease. These results suggest that 99mTc IDA may be used to determine the degree of functional disorder in acute hepatic disease and evaluate the severity of diffuse hepatic disease, whereas 99mTc colloid can effectively evaluate the potential etiology and chronicity of the disease.

Colloids↗
PubMed1999

Endoscopic resection of colloid cysts: surgical considerations using the rigid endoscope.

OBJECTIVE: Colloid cysts of the third and lateral ventricles have traditionally been treated by transfrontal and transcallosal microsurgical resection or by stereotactic aspiration. Recently, rigid and flexible ventricular endoscopic techniques have been used to treat these lesions. Our study was undertaken to examine the efficacy of rigid endoscopy in the resection of colloid cysts. METHODS: Fifteen patients with a radiological diagnosis of colloid cysts were given the option of undergoing either endoscopic surgery or craniotomy. The average tumor size was 1.43 cm. Fourteen patients underwent planned endoscopic resections, and a craniotomy was performed initially in one patient. RESULTS: Entire tumor resection was achieved with the endoscope in 12 patients (86%). A craniotomy was required for two colloid cysts that could not be resected endoscopically. In total, complete radiographic resections were achieved in 14 patients (93%). There were no permanent complications, although postoperative deficits included short-term memory loss and hemiparesis, each in one patient. CONCLUSION: Rigid endoscopy affords good optical resolution, high magnification, and excellent illumination. Total or near total resection of colloid cysts should be the goal for all patients and can be achieved using the rigid endoscope, with little morbidity, shortened operative time, reduced length of stay, and resolution of symptoms. Although long-term follow-up is needed, we think that endoscopy should be considered as a primary treatment for most patients.

Adult↗
PubMed2000

A theory on the natural history of colloid cysts of the third ventricle.

OBJECTIVE: Patients with third ventricular colloid cysts typically are diagnosed when they develop symptoms related to cerebrospinal fluid (CSF) obstruction at the foramen of Monro. However, the clinical and neuroimaging characteristics related to symptom development are poorly understood. METHODS: From January 1974 to June 1998, 155 patients with newly diagnosed colloid cysts were managed at our center. Eighty-seven patients (56%) were thought to have tumor-related symptoms, and they underwent surgery (resection, n = 74; ventriculoperitoneal shunting, n = 11; stereotactic aspiration, n = 2). Sixty-eight patients (44%) had colloid cysts thought to be asymptomatic, and observation with serial neuroimaging was recommended. Recursive partitioning was used to examine the association of patient and tumor characteristics with the development of cyst-related symptoms. RESULTS: Univariate analysis comparing symptomatic and asymptomatic patients revealed four factors associated with cyst-related symptoms: 1) younger patient age (44 yr versus 57 yr; P < 0.001); 2) cyst size (13 mm versus 8 mm; P < 0.001); 3) ventricular dilation (83% versus 31%; P < 0.001); and 4) increased signal on T2-weighted magnetic resonance images (44% versus 8%; P = 0.001). All four variables remained significant in a multivariate logistic regression model: patient age (P = 0.04; odds ratio, 1.0); cyst size (P = 0.04; odds ratio, 1.2); ventricular dilation (P = 0.02, odds ratio, 7.2); and increased signal on T2-weighted magnetic resonance images (P = 0.04; odds ratio, 2.7). The most significant variable was ventriculomegaly (yes versus no). Patients with normal-sized ventricles (n = 62) were further categorized by cyst size (< or = 10 mm versus > 10 mm). For patients with enlarged ventricles (n = 93), patient age (< or = 50 yr versus > 50 yr) was the most important variable. Patients older than 50 years also were split with respect to cyst size; patients aged 50 years or younger with enlarged ventricles were not affected by cyst size. The percentage of patients with cyst-related symptoms was 12, 50, and 85% in the three final patient classes, respectively. Multivariate analysis including the patient classes resulted in removal of the other significant variables from the model, whereas the patient classes remained significant (P < 0.0001; odds ratio, 6.3) for predicting patients with cyst-related symptoms. CONCLUSION: The patient and neuroimaging characteristics of the different patient classes support a theory on the natural history of colloid cysts. Patients with third ventricular colloid cysts become symptomatic when the tumor enlarges rapidly, causing CSF obstruction, ventriculomegaly, and increased intracranial pressure. Some cysts enlarge more gradually, however, allowing the patient to accommodate the enlarging mass without disruption of CSF flow, and the patient remains asymptomatic. In these cases, if the cyst stops growing, the patient can maintain a steady state between CSF production and absorption and may not require neurosurgical intervention.

Adult↗
PubMed2001

Delayed cerebrovascular complications of intrathecal colloidal gold.

OBJECTIVE: Therapy with intrathecal colloidal gold has been used in the past as an adjunct in the treatment of childhood neoplasms, including medulloblastoma and leukemia. We describe the long-term follow-up period of a series of patients treated with intrathecal colloidal gold and emphasize the high incidence of delayed cerebrovascular complications and their management. METHODS: Between 1967 and 1970, 14 children with posterior fossa medulloblastoma underwent treatment at the University of Minnesota. Treatment consisted of surgical resection, external beam radiotherapy, and intrathecal colloidal gold. All patients underwent long-term follow-up periods. RESULTS: Of the 14 original patients, 6 died within 2 years of treatment; all experienced persistent or recurrent disease. The eight surviving patients developed significant neurovascular complications 5 to 20 years after treatment. Three patients died as a result of aneurysmal subarachnoid hemorrhage, and five developed ischemic symptoms from severe vasculopathy that resembled moyamoya disease. CONCLUSION: Although therapy with colloidal gold resulted in long-term survival in a number of cases of childhood medulloblastoma, our experience suggests that the severe cerebrovascular side effects fail to justify its use. The unique complications associated with colloidal gold therapy, as well as the management of these complications, are presented. We recommend routine screening of any long-term survivors to exclude the presence of an intracranial aneurysm and to document the possibility of moyamoya syndrome.

Adolescent↗
PubMed1987

Scintigraphy of inflammation with nanometer-sized colloidal tracers.

The biodistribution of a nanometer-sized colloid was tested in three groups of rats, one with a turpentine-induced abscess and one with a histamine-induced oedema in the musculature of a hind leg. The third group served as a control. A 99Tcm-labelled colloid with a mean particle size of 30 nm was administered to each group intravenously. The biodistribution of the tracer, studied 1 h after injection, demonstrated that the colloid accumulated to a very limited extent in oedematous tissue, whereas the uptake in inflamed muscle was high. The colloid was subsequently administered to patients with arthritis, osteitis and osteomyelitis. All sites of inflammation accumulated the radiopharmaceutical and could be visualized scintigraphically 45 min after its administration. The results were in agreement with 67Ga-citrate or 111In-leukocyte scintigraphy, and/or other diagnostic modalities. Hyperaemia alone was not sufficient to cause uptake. We conclude that the mechanism of uptake is regional spilling of the tracer into the extravascular space through gaps in the damaged basement membrane, and that nanometer-sized 99Tcm-labelled colloid may constitute a convenient radiopharmaceutical for detecting inflammation in the extremities.

Animals↗
PubMedDate not supplied

Influence of volume replacement with colloids versus crystalloids in neonates on venoarterial extracorporeal membrane oxygenation on fluid retention, fluid balance, and ECMO runtime.

In this retrospective study, we compared the effects of colloid versus crystalloid fluid replacement on the clinical signs of capillary leakage syndrome in 30 neonates with pulmonary hypertension due to meconium aspiration syndrome on venoarterial membrane oxygenation (VA-ECMO). Before 2000, 15 neonates received volume replacement with a pasteurized plasma protein solution (3.8% albumin); after 2000, 15 neonates received normal saline. Patient characteristics and pre-ECMO values did not differ between the two groups. Total fluid balance was also equal. Diuretic use was significantly higher in the colloid group (p < 0.001). The chest wall soft-tissue index was significantly higher in the crystalloid group (p < 0.005), as were the ventilator settings at the end of the ECMO runtime (p < 0.05). Serum colloid osmotic pressure, albumin, urea nitrogen, and creatinine were significantly higher in the colloid group (p < 0.0001, < 0.0001, < 0.001, and < 0.05, respectively). Duration of VA-ECMO, of artificial ventilation after ECMO treatment, and the mortality rate did not differ between the two groups. We conclude that volume replacement with crystalloids in neonates on VA-ECMO aggravated the edema in a preexisting situation of capillary leakage syndrome, whereas volume replacement with colloids could impair the kidney function.

Capillary Leak Syndrome↗
PubMed2003

Freezing transition and correlated motion in a quasi-two-dimensional colloid suspension.

Recent experiments have demonstrated that the deviation of the single-particle displacement distribution from Gaussian form in a dense quasi-two-dimensional colloid suspension is a result of heterogenous dynamics that involves cooperative motions of neighboring colloid particles [J. Chem. Phys. 47, 9142 (2001)]. In this paper, we report the results of molecular dynamics (MD) simulations of a quasi-two-dimensional assembly of nearly hard-sphere colloid particles. The colloid-colloid interaction we use is short ranged and everywhere repulsive; it is related to the Marcus-Rice (MR) and modified MR interactions used in a previous study [Phys. Rev. E 58, 7529 (1998)]. As is the case for those systems, the one we study supports liquid, hexatic, and solid phases. Our calculations show that the deviation of the single-particle displacement distribution from Gaussian form is present in the liquid phase, and that a sharp increase in its magnitude occurs at the liquidus density and extends into the crystalline phase. For densities greater than the liquidus density we find three dynamical relaxation processes that include, at intermediate times, a slowing down in the rate of growth of the diffusive displacement of a particle due to the cage effect. As the density increases toward the solidus density, the dependence of the mean squared displacement on time, at intermediate times, changes from sublinear to zero. The onset of the long-time relaxation mode corresponds to the time at which the deviation of the particle displacement distribution from Gaussian form is a maximum. At this time, which increases exponentially with the density, the self-part of the van Hove function exhibits multiple maxima with respect to r while the distinct part of the van Hove function is a maximum at the origin, thereby signaling jump dynamics. At long times the particle mean square displacement has diffusive character at all densities including solid phase densities. A remarkable feature of our findings is the continuity of character of the particle displacement from the liquid phase through the hexatic phase and into the solid phase. Cooperative jumps that lead to diffusive process in crystals can be explained by a mechanism that involves many such correlated hops in random locations and random directions (but along the crystallographic axes) thereby generating effective random walk behavior. We argue that the collective motion we have found is generated by superpositions of instantaneous normal mode vibrations along diffusive paths. The diffusive paths are along the directions with strong bond orientation correlation, and start to grow in amplitude rapidly on entry into the hexatic phase.

Biophysical Phenomena↗
PubMed2002

Microscopics of complexation between long DNA molecules and positively charged colloids.

Extensive atomic force and electron microscopy reveal a new, generic DNA-colloid complex with a fixed number of DNA bases per colloid. The fiber shaped complex is stable in the presence of excess colloids in the solution. As more DNA is added to the solution and the ratio between colloids and DNA approaches the fiber's stoichiometry, the system undergoes a sharp coagulation transition. The system is restabilized at even higher DNA concentrations through localization of small colloid clusters on extensive DNA networks.

Bacteriophage lambda↗
PubMed2004

XAFS study of americium sorbed onto groundwater colloids.

The sorption of americium, as Am(III), onto groundwater colloids obtained from a marl aquifer was studied in 2 x 10(-2)M sodium bicarbonate groundwater and 2 x 10(-2)M sodium chloride bicarbonate-free solutions. At the in situ groundwater pH of 8.6, the americium was strongly sorbed onto the colloids. XAFS analyses were performed on these sorbed Am species to establish the oxidation state and its near-neighbour bonding. These XAFS data, obtained at 400 mg l(-1) colloid concentrations and total Am concentration of 1.53 x 10(-5)M (dissolved and onto colloids), indicated that Am remains trivalent, and that surface complexes are formed with the colloids without surface precipitation. This conclusion is based on the absence of Am-Am interactions in the second or third shells. The surface complexes generated by the Am(III) sorbed onto active sites are described on the basis of the XAFS data. They include the presence of about seven water molecules around the ternary surface complexes of this trivalent actinide.

Adsorption↗
PubMed1988

Differential staining of skin-limited amyloid and colloid bodies with immunofluorescence after pretreatments.

We examined whether immunoglobulin (Ig) and complement (C) components of amyloid and colloid bodies were inherent parts of these substances or were present due to nonspecific absorption only. In direct immunofluorescence (IF) studies without pretreatment, skin-limited and systemic amyloid and colloid bodies in all cases showed positive staining for Ig or C. When these sections were pretreated with 0.1 M glycine buffer (pH 7.2) or 0.05% Tween-20 solution, Ig and C in skin-limited amyloid deposits were negative or weakly positive. In contrast, positive fluorescence of colloid bodies and systemic amyloid masses was not influenced by pretreatment. Existence of amyloid masses before and after pretreatment were confirmed by Thioflavin-T and Dylon stains. In addition, pretreatment did not alter disulfide bonds by DACM staining or the reactivities of amyloid with monoclonal antikeratin antibody EKH4. These results suggest that skin-limited amyloid can be differentiated from systemic amyloid or colloid bodies by these methods. We can infer from the present studies that most of the Ig and C in skin-limited amyloid masses are a result of nonspecific absorption due to penetration of serum, which is different from Ig in systemic amyloid and colloid bodies in as much as in these conditions immunobinding is specific.

Amyloid↗
PubMed1978

Physical forces in blister formation. The role of colloid osmotic pressure and of total osmolality in fluid migration into the rising blister.

The physical forces operative in the fluid migration from the interstitial spaces into the blister cleft have not been directly measured until now. The colloid osmotic pressure and the total osmolality were determined in suction blister fluid after mild suction blister production by a modified "Dermovac" and in blister fluid of patients with dermatitis herpetiformis, bullous allergic contact dermatitis and pemphigus vulgaris and in the sera of healthy persons. The colloid osmotic pressure was measured by means of a recently developed osmometer with a semipermeable membrane between 2 chambers, one of them filled with Ringer solution, the other with the blister fluid or serum sample. The negative pressure in the first chamber was determined. The colloid osmotic pressure of suction blister fluid averages approximately 7 cm H2O, the values reach about 20 cm H2O in bullous diseases and about 38 cm H2O in the normal sera. The blister fluid colloid osmotic pressure has to rise to about 15 cm H2O or more to cause the fluid transport from the interstitial spaces of the surrounding tissue into the blister because of the negative interstitial fluid pressure and the colloid osmotic pressure of the interstitial fluid. Otherwise the blister fluid is reabsorbed back into the interstitial spaces. The total osmolality does not differ in the serum and in the blister fluid. It does not seem to be etiologically connected with the fluid transport into the rising blister.

Blister↗
PubMed1985

Colloid milium: a final degeneration product of actinic elastoid.

Serum amyloid P component (SAP) is present not only in all types of cutaneous amyloidosis, but also in the normal dermal elastic fibers as well as abnormal elastic fibers, such as elastotic degeneration of elastic fibers in actinic keratosis. It was previously postulated that the colloid substance in colloid milium is a final degeneration stage of actinic elastosis. In a lesion of colloid milium SAP was intensely positive with an indirect immunofluorescence method using rabbit antiserum to human SAP. Electron microscopy of the colloid lesion revealed components of normal elastic fibers as well as those of actinic elastoid as seen in actinic elastosis. It is concluded that the colloid substance derives, at least in major part, from elastic fibers through actinic degeneration.

Aged↗
PubMedDate not supplied

Colloid mobilization in the field using citrate to remediate chromium.

We investigated the feasibility of cleaning aquifer sediments, long contaminated with chromium (Cr) from a metal plating facility, by detaching colloid-sized sorbents from the immobile aquifer solids and then pumping those colloids to the surface for treatment. In laboratory experiments using aquifer solids from the site, several solutions (water at various pHs, phosphate, oxalate, ascorbate, citrate) were examined for their ability to disperse colloids and Cr. Based on these tests, a 5 mM citrate solution at pH 7 was selected. Subsequently, such a citrate solution was used in the field in two single-well injection-withdrawal experiments. Large quantities of colloids were released immediately after injection. The colloidal particles mobilized by citrate in the field had more than 20 times higher Cr concentrations than did the average aquifer sediments, implying success in mobilizing Cr-associated phases. Further, laboratory and field tests showed that anion exchange of citrate for chromate caused some additional release of Cr from these aquifer solids.

Chelating Agents↗
PubMed1984

Colloidal gold and biotin-avidin conjugates as ultrastructural markers for neural antigens.

The use of two new reagents, biotin-avidin conjugates and colloidal gold particles, for ultrastructural immunocytochemistry has been reviewed, and their potential for immunocytochemistry in the central nervous system has been discussed. Although these compounds have been used very little in the C.N.S. in the past, with their high sensitivity, versatility, and potential for simultaneous localization of two antigens with two electron dense markers, these reagents may prove very useful for answering a number of neural questions. Colloidal gold adsorbed to immunoglobulins can be used for light microscopic observation, and owing to its high electron density and ability to readily adsorb to immunoglobulins, protein A, and antigen-carrier complexes, it also serves as an excellent immunomarker at the ultrastructural level. Several procedures have been described for the use of pre- and post-embedding immunostaining with colloidal gold particles. Different size gold particles, adsorbed to different antibodies can be used for pre- and post-embedding staining of different antigens in the same tissue. While at the light microscopic level only the large particles are visible as a pink haze, a fluorescent step can be added to allow easy identification and characterization of neurones labelled with any size colloidal gold, even if the pink colour of the gold is not visible. These same sections can subsequently be studied ultrastructurally. Unlike enzymatic methods, gold particles have less tendency to obscure ultrastructure. Biotin can be easily conjugated to immunoglobulins and, due to its high affinity for avidin (10(15) M-1) which has four biotin binding sites, can be localized with avidin markers, or biotin-avidin-marker complexes. Some procedures such as the avidin-biotin-peroxidase complex are extremely sensitive. Biotin and avidin can be bound to a number of different markers including peroxidase, colloidal gold, and ferritin. Photomicrographs from our hypothalamic work have been used to illustrate the histological results of some of the procedures described.

Animals↗
PubMed1985

Uptake and subcellular localisation of bismuth in the gastrointestinal mucosa of rats after short term administration of colloidal bismuth subcitrate.

Despite the topical action of colloidal bismuth subcitrate in promoting the healing of peptic ulcers, slight absorption of bismuth from the gastrointestinal tract has been reported in colloidal bismuth subcitrate-treated animals and man. The uptake and subcellular distribution of bismuth by the gastrointestinal tract of rats after 24 hours of colloidal bismuth subcitrate administration was studied. Mucosal uptake of bismuth (mean +/- SEM nmol/g protein) by gastric fundus (8.85 +/- 1.0) and antrum (7.23 +/- 1.50) was similar, but was significantly less than duodenum (19.2 +/- 3.7, p less than 0.05), jejunum (26.9 +/- 2.4, p less than 0.001) or ileum (22.4 +/- 2.2, p less than 0.001). Bismuth concentrations in antral and duodenal mucosae fell progressively over 72 hours to approximately 10% of initial concentrations (p less than 0.02). Subcellular fractionation studies of colloidal bismuth subcitrate treated duodenal enterocytes showed a brush border membrane and cytosolic localisation. These data suggest that some gastrointestinal mucosal uptake of bismuth occurs in colloidal bismuth subcitrate treated rats.

Animals↗
PubMed2004

Colloidal aggregation with sedimentation: concentration effects.

The results of computer models for colloidal aggregation, that consider both Brownian motion and gravitational drift experienced by the colloidal particles and clusters, are extended to include concentrations spanning three orders of magnitude. In previous publications and for a high colloidal concentration, it was obtained that the aggregation crosses over from diffusion-limited colloidal aggregation (DLCA) to another regime with a higher cluster fractal dimension and a speeding up followed by a slowing down of the aggregation rate. In the present work we show, as the concentration is decreased, that we can still cross over to a similar regime during the course of the aggregation, as long as the height of the sample is increased accordingly. Among the differences between the mentioned new regimes for a high and a low colloidal concentration, the cluster fractal dimension is higher for the high concentration case and lowers its value as the concentration is decreased, presumably reaching for low enough concentrations a fixed value above the DLCA value. It is also obtained the fractal dimension of the sediments, arising from the settling clusters that reach the bottom and continue a 2D-like diffusive motion and aggregation, on the floor of the container. For these clusters we now see two and sometimes three regimes, depending on concentration and sedimentation strength, with their corresponding fractal dimensions. The first two coming from the crossover already mentioned, that took place in the bulk of the sample before the cluster deposition, while the third arises from the two-dimensional aggregation on the floor of the container. For these bottom clusters we also obtain their dynamical behavior and aggregation rate.

Algorithms↗
PubMed1980

Simultaneous comparison of canine tracheal transport of anion exchange resin particles to albumin macroaggregates and sulfur colloid. Effects of subcutaneous methacholine chloride and intravenous hypertonic saline.

We compared simultaneously measured canine tracheal transport rates of Dowex anion exchange particles with macroaggregates of albumin, and with sulfur colloid. We found that sulfur colloid moved significantly faster than large Dowex particles (diameter 180 micrometer), which had transport rates similar to macroaggregates of albumin, and small Dowex particles diameter 3 micrometer). We examined the alteration of airway fluid caused by intravenous 5% saline or subcutaneous methacholine chloride. We then studied the effects of the altered airway fluid on the transport rates of large Dowex particles and sulfur colloid. We found that sulfur colloid continued to be transported faster than Dowex particles. Although we do not have an explanation for the faster transport of sulfur colloid, we believe that the physiochemical properties of the marker may influence its rate of tracheal transport.

Albumins↗
PubMed2002

Organic-inorganic nanostructured colloids.

The synthesis and applications of organic-inorganic nanostructured colloids and colloidal-based materials are reviewed here. Emphasis is placed on the strategies and synthetic methods developed to organize organic-inorganic architectures. The article begins with a description and a general hierarchical classification of different systems, from inorganic particle synthesis and surface modification to more elaborate nanostructured colloids obtained through in situ encapsulation and/or self-assembly techniques. Ordering of colloids into two- and three-dimensional arrays and their use as templates is also considered. For every system, typical examples are given that highlight the advantages and limitations of the techniques, as are more recent developments. Some properties and applicability of organic-inorganic colloids in catalysis, medicine, and coating technologies are also cited.

Colloids↗